In a typical thermal printer, a web-type dye carrier containing a repeating series of spaced frames of different colored heat transferable dyes is spooled on a supply spool. The carrier is paid out from the supply spool and rewound on a take-up spool. The carrier moves through a nip formed between a thermal print head and a dye-absorbing receiver. The receiver in turn is supported by a platen. The print head engages the dye-carrier and presses it against the receiver. The receiver may, for example, be coated paper and the print head is formed of, for example, a plurality of heating elements. When a particular heating element is energized, it is heated. In the presence of heat and pressure, dye from the carrier is caused to transfer to the dye-received. The density or darkness of the printed color dye is a function of the energy delivered from the heating element to the carrier.
The web-type carrier often includes a repeating series of spaced yellow, magenta and cyan dye frames. The carrier is typically formed of a very thin, flexible dye carrying web having a thickness that can be on the order of one fourth mil. Both the supply and the take-spool for the dye carrier web are typically mounted in a cartridge. Even though the carrier is very thin and has no beam strength, positioning and handling the dye carrier web in a printer with such a cartridge is not a problem since both ends of the carrier are already wound on the supply and take-up spool.
The dye-absorbing receiver may be supplied as a package of pre-cut sheets of coated paper which are fed into the printing nip by a paper pick and transport system. In some thermal printers, a roll of receiver media is used to supply the dye-receiver rather than a pre-cut sheet of dye-receiver in order to reduce the media manufacturing cost. In such a system, an image is printed on the dye-receiver that is still attached to the roll and the receiver is cut from the supply roll after each image is printed. The supply roll pays out the receiver for each color, then rewinds it back up before the next color.
A printing system that utilizes the separate dye carrier and receiver packs for the thermal printing media has several drawbacks. First, the printing apparatus tends to be overly complex since the system requires separate mechanisms to handle the media, one mechanism to handle the dye carrier and another to transport the receiver. Second, in addition to the increased inconvenience to the customer, there are greater chances to mishandle the media and damage the printer since one has to handle the media twice; once to load the dye carrier and once to load the receiver. Some receivers require special dye carriers, receiver media combinations for unique image printing. If the media in the printer comes in two separate packages, there is a possibility that one could mismatch media and ruin the uniqueness of the print.
European Patent Application No. 0 487 314 Published 27.05.92 by Collins shows a cassette for thermal printer that prints a single color of ink on a narrow ribbon. The cassette includes an ink ribbon wound on a supply spool and received on a take up spool in the cassette. The cassette also includes a roll of ink receiving tape. A problem with such a design is that the cartridge becomes quite large, particularly for full color thermal printing in wide formats, thereby increasing the cost of packaging, storage and handling of the media cassette.
There is a need therefore for an improved media pack of a color thermal printer.